In a gas turbine engine, compressor blades are attached to a rotating disk with the blade tips as close as possible to the "endwall". Different sealing techniques are used to minimize the adverse effects of tip-endwall clearance and tip rub on the seal. Compressor rotor blade tip-endwall clearance growth significantly reduces compressor stall margin, mainly due to leakage between the pressure and suction sides of the blade. That leakage reduces total streamwise flow momentum through the blade passage, reducing blade pressure rise capability and therefore stall margin. A plot of pressure across the blade from root to tip would show a drop in total pressure towards the tip, due to that leakage. Stall margin loss from clearance increases perhaps arises from an interaction between the endwall and the blade suction side boundary layers, a condition that potentially could cause boundary layer flow separation on the suction side, causing flow blockage in that area.